1. Technical Field
The present disclosure relates to a method for fabricating a carbon nanotube film.
2. Description of Related Art
Carbon nanotubes are tubules of carbon generally having a diameter of 0.5 to 100 nanometers, and composed of a number of coaxial cylinders of graphite sheets. Carbon nanotubes have interesting and potentially useful thermal, electrical and mechanical properties, and have recently attracted a great deal of attention for use in different applications such as field emitters, gas storage and separation, chemical sensors, and high strength composites. However, the main obstacle to an actual application of carbon nanotube use is their difficulty to process, due to the powder form of the carbon nanotube products. Therefore, carbon nanotubes are formed into films to facilitate handling and processing thereof.
A method for drawing a carbon nanotube film is disclosed in US patent application NO. 2008/0248235A1 to Feng et al., published on Oct. 9, 2008. This patent publication discloses the carbon nanotube film which is directly drawn from a carbon nanotube array by a tool. The drawn carbon nanotube film includes a plurality of successively oriented carbon nanotube segments joined end-to-end by van der Waals attractive force therebetween. Each carbon nanotube segment includes a plurality of carbon nanotubes substantially parallel to each other, and joined by van der Waals attractive force therebetween. This carbon nanotube film is a free standing film because the adjacent carbon nanotube segments are joined end-to-end by van der Waals attractive force therebetween. The carbon nanotube film is fabricated by using a selecting tool, such as an adhesive tape, to contact the carbon nanotube array; and pulling the carbon nanotubes at an even speed to form the carbon nanotube film. The carbon nanotube segments will be successively pulled out and joined end to end.
Generally, the carbon nanotube film manufactured by the above method is transparent. However, when the speed of pulling the carbon nanotube film is relatively fast, defects may form in the carbon nanotube film. The quality of the carbon nanotube film, such as its uniformity, is largely affected by the speed of pulling the carbon nanotube film. For example, if the speed of pulling is too fast, adjacent segments may not be firmly joined, some of the carbon nanotube segments may detach from the carbon nanotube film, or form clusters. Thus, the carbon nanotube film has a lower uniformity.
What is needed, therefore, is to provide a method for pulling the carbon nanotube film with fewer defects at a relatively fast speed.